Making a bootable OpenBSD install CD

Most newish i386 computers can boot from the CDROM. These instructions outline how to create a bootable CDROM for installing OpenBSD.

Get your files organised. The OpenBSD installer expects to see a CDROM with a directory structure of /version_number/architecture/, where version_number is the current version, and architecture is i386. For a minimal boot image, all that's needed are the tarred gzipped install files, the bsd kernel, and the cdromxx.fs floppy image.

These files need to be arranged in a directory, e.g.

mkdir OpenBSD
mkdir OpenBSD/3.8
mkdir OpenBSD/3.8/i386

Copy the files into the OpenBSD/3.8/i386 directory.

The FTP and HTTP mirrors of OpenBSD come pre-arranged in the proper manner. To get all the needed files I just wget -r ftp://whatever.mirror/pub/OpenBSD/3.8/i386 and all the files are copied over complete with the correct structure.

Now all you need is to use mkisofs to create an iso image. The command to do this is:

mkisofs -r -b 3.8/i386/cdrom38.fs -c "boot.catalog" -o OpenBSD.iso OpenBSD

This command creates a ISO9660 CD with Rock Ridge extensions, which will boot from the floppy image in cdrom38.fs. The image is output to OpenBSD.iso. You can then burn this onto a CDROM with anything that knows how to burn ISO images. I've used cdrecord on OpenBSD, or copied the file onto a Windows box and used the recording software there.

Philip Plane philip@xinqu.net